Approach to Radiative Heat Transfer in Infrared-active Gas Including Scattering Particles through a Direct Solution Method of the Maxwell's Electro-Magnetic Equation

粒子散射辐射能量的散射模式随粒子数密度的变化而变化。在数字密度增加的第一阶段，散射能强度在小散射角范围内下降。但在大散射角范围内，散射能不出现下降。在数密度增加的下一阶段，散射能在小散射角范围内下降明显，在大散射角范围内散射强度下降的区域变宽。当散射强度的衰减达到衍射区的边缘时，在整个散射角范围内都可以识别出散射强度的衰减。在整个散射角范围内，当散射物体的数量密度增大时，散射强度明显减小。这意味着基于单个粒子形成的散射模式的相函数在散射粒子数密度很高且多重散射效应的影响正在储存时不能使用。对于散射粒子数密度，粒子间距离沿光轴方向加宽时，多重散射效应消失得比沿垂直光轴方向加宽时快。在后一种情况下，阐明了多重散射效应消失的散射角间的临界距离。在可以忽略多次散射影响的情况下，通过将多个相同形状的散射物体在任意姿态下形成的散射模式反演为粒子尺寸分布，考察了粒子形状的影响。当散射物体的长度保持直径不变时，等效球体的平均直径和尺寸分布方差变大。但是，粒子越长，平均直径和方差的变化就越温和。当粒子形状为旋转椭球体时，粒径分布的方差很小，散射模式反演得到的平均直径相当于任意姿态粒子形成的投影形状平均值的圆直径，该圆的面积相同。电磁方程的直接有限差分解法可以预测散射粒子间的电磁场，而米氏散射理论不能预测。另一方面，电场E与磁场H的外积表示各方向能量通量的矢量复合。因此，如何从有限差分解法得到的电磁场中知道辐射强度并没有得到明确的说明。这个问题在这次调查中得到了解决。少

Scattering pattern of radiative energy scattered by particles varies with number density of particles. At the first stage of increase in number density, the intensity of scattered energy drops in the range of small scattering angle. But, the decline of scattered energy does not appear in the range of large scattering angle. In the next stage of increase in number density, the decline of scattered energy becomes remarkable in the rage of small scattering angle, and the region of fall down in scattering intensity becomes wide toward the range of large scattering angle. When the decline of scattering intensity reaches to the edge of diffraction region, the decline of scattering intensity can be recognized over the whole range of scattering angle. When the number density of scattering objects becomes much higher, scattering intensity goes down remarkably over the whole range of scattering angle. This means that the phase function based on the scattering pattern formed by a single particle … More can not be used when the number density of scattering particles are very high and the influence of multiple-scattering effect is storing. As for the number density of scattering particles, the effect of multiple scattering disappears more quickly when the distances among particles is widened in the direction of optical axis than when widened in the direction perpendicular to the optical axis. In the latter case, the critical distances among scattering angle where the multiple-scattering effect disappears is clarified.On condition that the effect of multiple scattering can be neglected, the influence of particle shape was examined by inverting the scattering pattern formed by plural scattering objects of same shape existing in arbitrary posture into particle size distribution. When the length of scattering objects is extended keeping the diameter, the mean diameter and variance of size distribution of equivalent spheres become large. But, the longer becomes the particle, variation in the mean diameter and variance becomes more moderate. When the shape of particles is rotating ellipsoid, the variance of size distribution is very small and the mean diameter obtained from the inversion of scattering pattern is equivalent to the diameter of a circle having same area as the average of projected shapes formed by the particle of arbitrary posture.Direct finite difference solution method of the electro-magnetic equation can predict the electromagnetic field among scattering particles though the Mie's scattering theory cannot predict it. On the other hand, the external product of electric field E and magnetic field H means the vector compound of energy flux in all direction. Therefore, it was not clarified how to know the radiative intensity from the electro-magnetic field obtained from the finite difference solution method. This problem was solved in this investigation. Less